In the book it points out that the exhaust outlets on the class 42 Swindon locos were in the middle of the roof section, saying that this 'explains' why they were not allowed under lines with catenary, such as the WCML. Is this true? there are several images of these locos at Crewe and even on China Clay trains through the Midlands. There are even incidences of them getting into the Merseyside area. Not meant as a criticism of this bookazine, which I enjoyed incidentally, just wondering if this was an official policy that was not always strictly adhered to...